Subsections

- Library
- Description
- Dialog Box
- Default properties
- Interfacing function
- Computational function (type 4)

##
Signum

### Library

Non_linear

### Description

The Sign block indicates the sign of the input:

- The output is 1 when the input is greater than zero.
- The output is 0 when the input is equal to zero.
- The output is -1 when the input is less than zero.

### Dialog Box

Set block parameters |
use zero_crossing (1: yes) (0:no) | 1

- use zero_crossing : 0 or 1

### Default properties

- always active: no
- direct-feedthrough: yes
- zero-crossing: yes
- mode: yes
- number/sizes of inputs: 1 / -1
- number/sizes of outputs: 1 / -1
- number/sizes of activation inputs: 0 /
- number/sizes of activation outputs: 0 /
- continuous-time state: no
- discrete-time state: no
- name of computational function: signum

### Interfacing function

`scilab/macros/scicos_blocks/nonlinear/SIGNUM.sci`

### Computational function (type 4)

    #include "scicos_block.h"
    #include <math.h>

    void  signum(scicos_block *block,int flag)
    {
      int i,j;
      if (flag==1){
        for(i=0;i<block->insz[0];++i){
          if (get_phase_simulation()==1||block->ng==0) {
    	if (block->inptr[0][i]<0){
    	  j=2;
    	} else if (block->inptr[0][i]>0){
    	  j=1;
    	}else{
    	  j=0;
    	}
          }else {
    	j=block->mode[i];
          }
          if (j==1){
    	block->outptr[0][i]=1.0;
          } else if(j==2){
    	block->outptr[0][i]=-1.0;
          }else{
    	block->outptr[0][i]=0.0;
          }
        }
      }else if (flag==9){
        for(i=0;i<block->insz[0];++i){
          block->g[i]=block->inptr[0][i];
          if (get_phase_simulation()==1) {
    	if(block->g[i]<0){
    	  block->mode[i]=2;
    	}else{
    	  block->mode[i]=1;
    	}
          }
        }
      }
    }